Amazingly enough, there is still an actively supported Lineage OS for my old Galaxy Nexus. It's LOS 13.0 which is only 6.0.1....wait...my Note 4 will be stuck on 6.0.1 forever too.
Anyways it's a fun little experiment device. I'm just playing around with Magisk and seeing how modern systemless root works. Fun fact: It's possible to root with Magisk, install Adaway, edit your Hosts file to block ads, and then uninstall Magisk to completely unroot but keep your ad blocking because the Hosts file persists.
Ad blocking is the only thing I still use root for these days, so this is a nice little trick for people who play games like Pokemon Go which have an aneurysm if you're rooted. MagiskHide doesn't always work so if all you need is ad blocking, this is a good alternative. I'm assuming taking OTA's will overwrite your Hosts file, testing that now with the latest LOS OTA Nightly, requiring me to install Magisk, block ads again, and uninstall it every month if I were taking OTA's every month for Android security updates.
edit:
Huh, LOS OTA's don't overwrite your Hosts file. Well shit, this is too easy for LOS users. I wonder if Google's stock Android OTA's on Nexus/Pixel overwrite your Hosts file. One of you guys should test using my method and see if you can keep ad blocking through security updates!